Samsung U60J620DAF Power and Backlights blink

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  • MEB
    Badcaps Veteran
    • Sep 2013
    • 371
    • USA

    #21
    Re: Samsung U60J620DAF Power and Backlights blink

    Thanks Bud, I will get one from somewhere, install and report back.

    Comment

    • jason123
      Badcaps Legend
      • Oct 2015
      • 1040
      • USA

      #22
      Re: Samsung U60J620DAF Power and Backlights blink

      Happy to do it.. pm me your address

      Comment

      • MEB
        Badcaps Veteran
        • Sep 2013
        • 371
        • USA

        #23
        Re: Samsung U60J620DAF Power and Backlights blink

        Thanks. Address on the way.

        Comment

        • jason123
          Badcaps Legend
          • Oct 2015
          • 1040
          • USA

          #24
          Re: Samsung U60J620DAF Power and Backlights blink

          in the mail today! sorry wasn't able to make to the post office yesterday

          Comment

          • MEB
            Badcaps Veteran
            • Sep 2013
            • 371
            • USA

            #25
            Re: Samsung U60J620DAF Power and Backlights blink

            Thanks jason123 for the diode. It came today. Measured resistance on new diode. Measured 0L one way and 292K ohms the other. Diode test revealed 0L and .497VDC. Assuming this diode to be good, I placed it in the power supply board, connected everything back up and upon plugging in to AC, symptoms are unchanged. Power light and backlights flash repeatedly in unison every second or so.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #26
              Re: Samsung U60J620DAF Power and Backlights blink

              Can you do the diode resistance reading again with it solder in place?
              Never stop learning
              Basic LCD TV and Monitor troubleshooting guides.
              http://www.badcaps.net/forum/showthr...956#post305956

              Voltage Regulator (LDO) testing:
              http://www.badcaps.net/forum/showthr...999#post300999

              Inverter testing using old CFL:
              http://www.badcaps.net/forum/showthr...er+testing+cfl

              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
              http://s807.photobucket.com/user/budm/library/

              TV Factory reset codes listing:
              http://www.badcaps.net/forum/showthread.php?t=24809

              Comment

              • MEB
                Badcaps Veteran
                • Sep 2013
                • 371
                • USA

                #27
                Re: Samsung U60J620DAF Power and Backlights blink

                Thanks for the reply. I will do this tonight when I get home and report back.

                Comment

                • MEB
                  Badcaps Veteran
                  • Sep 2013
                  • 371
                  • USA

                  #28
                  Re: Samsung U60J620DAF Power and Backlights blink

                  OK, with black on cathode reads a constant 287.8K ohms. Reversing the leads so red is on cathode, starts around 300-400K ohms and just keeps increasing.

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #29
                    Re: Samsung U60J620DAF Power and Backlights blink

                    That is fine, just have to look deeper in that LED driver section next.
                    Never stop learning
                    Basic LCD TV and Monitor troubleshooting guides.
                    http://www.badcaps.net/forum/showthr...956#post305956

                    Voltage Regulator (LDO) testing:
                    http://www.badcaps.net/forum/showthr...999#post300999

                    Inverter testing using old CFL:
                    http://www.badcaps.net/forum/showthr...er+testing+cfl

                    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                    http://s807.photobucket.com/user/budm/library/

                    TV Factory reset codes listing:
                    http://www.badcaps.net/forum/showthread.php?t=24809

                    Comment

                    • MEB
                      Badcaps Veteran
                      • Sep 2013
                      • 371
                      • USA

                      #30
                      Re: Samsung U60J620DAF Power and Backlights blink

                      Here are some better pictures of the front and back of PS. Am currently trying to read up on LED Driver circuits and will attempt to trace circuit on board.
                      Attached Files

                      Comment

                      • MEB
                        Badcaps Veteran
                        • Sep 2013
                        • 371
                        • USA

                        #31
                        Re: Samsung U60J620DAF Power and Backlights blink

                        Am trying to make a schematic of the LED Driver section of BN4400775A power supply for this TV. I ran across a 7014X which is addressed on the board as IC9151. I can not find a datasheet for him, but this one keeps popping up in my hunt. OB2268/9. It is a PWM Controller with 8 pins like the 7014X. I don't know if this is just a coincidence or if I have run across something useful. I searched for 7014X on this site, but only found it mentioned on jason123 post about his Samsung, but it wasn't his problem. May still have to get into the LEDs, but figure I might try to learn something along the way.
                        Attached Files

                        Comment

                        • MEB
                          Badcaps Veteran
                          • Sep 2013
                          • 371
                          • USA

                          #32
                          Re: Samsung U60J620DAF Power and Backlights blink

                          Found a broken display TV identical to mine on Craig's list. Took the PS and put it in mine. Same flashing backlights issue. Bought this little led tester thing which is advertised everywhere. The TV has 2 strings. Using the tester on one string at a time disconnected from the power supply, both strings lit up and stayed on but at a low level as seen through the holes on the back of the display. Both strings had the exact same reading of 107 on the tester. Am not really sure what the 107 DC means. Looking for input before I disassemble the display. Thanks.

                          Comment

                          • budm
                            Badcaps Legend
                            • Feb 2010
                            • 40746
                            • USA

                            #33
                            Re: Samsung U60J620DAF Power and Backlights blink

                            107 V is the Forward Voltage of the LED string @30mA of driven current.
                            Never stop learning
                            Basic LCD TV and Monitor troubleshooting guides.
                            http://www.badcaps.net/forum/showthr...956#post305956

                            Voltage Regulator (LDO) testing:
                            http://www.badcaps.net/forum/showthr...999#post300999

                            Inverter testing using old CFL:
                            http://www.badcaps.net/forum/showthr...er+testing+cfl

                            Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                            http://s807.photobucket.com/user/budm/library/

                            TV Factory reset codes listing:
                            http://www.badcaps.net/forum/showthread.php?t=24809

                            Comment

                            • MEB
                              Badcaps Veteran
                              • Sep 2013
                              • 371
                              • USA

                              #34
                              Re: Samsung U60J620DAF Power and Backlights blink

                              Thanks, bud.

                              In summation.

                              -TV On - Backlights flash on and off in sync with the front power light.
                              -Got new PS - exact same symptoms.
                              -Got LED tester - Can light all strings from power supply end. Can"t verify they are all lit through the back holes, but each string stays on steady.
                              -Assuming it was LEDs, obtained 12 new strips from SJ, disassembled panel. -Using tester all original LEDs tested good.
                              -Figured I had gone this far, I would put in new strips anyway. Installed, all new strips tested OK and I could light both strings from the PS connector.
                              Assembled panel and connected everything.
                              -Saw one brief flash of light and powering up over and over did nothing.
                              -Removing wires from PS connector, top string won't light, but lower string will.

                              -Swore alot then disassembled panel.
                              -There are 6 rows of strips. Top 3 compose one string, bottom the other.
                              - From the power supply end, the top strips do not light, but the lower 3 will.
                              -Tested each strip individually. Top strip is dead. No Leds light. 2nd strip has 5 good LEDs and the 3rd strip is OK.

                              What in the world have I done? Right now, I have 2 PS boards, the old strips which seem to be working, 2 dead strips and 3 new strips.

                              I contemplated about putting the old strips back in, but seems like I am just going in circles. Appreciate some help.

                              Comment

                              • nomoresonys
                                Badcaps Legend
                                • Jan 2013
                                • 12085
                                • U.S.

                                #35
                                Re: Samsung U60J620DAF Power and Backlights blink

                                Wonder if the new strips were faulty before you installed them, did you test them?

                                Comment

                                • MEB
                                  Badcaps Veteran
                                  • Sep 2013
                                  • 371
                                  • USA

                                  #36
                                  Re: Samsung U60J620DAF Power and Backlights blink

                                  Yes, I tested them before and after I installed them prior to putting the panel back together. The only connections I had to make was the LED connector to the PS and the AC.

                                  Comment

                                  • nomoresonys
                                    Badcaps Legend
                                    • Jan 2013
                                    • 12085
                                    • U.S.

                                    #37
                                    Re: Samsung U60J620DAF Power and Backlights blink

                                    So with everything unplugged from powerboard, you do have steady 8 volts on standby pin on CNM803?

                                    Comment

                                    • MEB
                                      Badcaps Veteran
                                      • Sep 2013
                                      • 371
                                      • USA

                                      #38
                                      Re: Samsung U60J620DAF Power and Backlights blink

                                      Thanks for the reply. I left my meter at work. The only one I have at home has rechargeable batteries and it might be awhile. I will get back to you.

                                      Comment

                                      • MEB
                                        Badcaps Veteran
                                        • Sep 2013
                                        • 371
                                        • USA

                                        #39
                                        Re: Samsung U60J620DAF Power and Backlights blink

                                        Pin 1 - UD - +13V
                                        Pin 3 - PWM-BLU - +13V
                                        Pin 5 - PS_ON - +13V
                                        Pin 7 - +13V
                                        Pin 9 - GND = 0 volts

                                        These were taken with the black lead on pin 10 GND.
                                        PS board is only attached to AC.

                                        Comment

                                        • MEB
                                          Badcaps Veteran
                                          • Sep 2013
                                          • 371
                                          • USA

                                          #40
                                          Re: Samsung U60J620DAF Power and Backlights blink

                                          For information, I did the same to the other PS board I have and got identical results.

                                          Comment

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